With a growing quantity of electronic devices, an electromagnetic interference (EMI) phenomenon is increasingly severe. EMI conducted interference includes common-mode interference. To resolve an EMI common-mode interference problem, a conventional method is to add a passive EMI common-mode filter (including a common-mode inductor and a Y capacitor) to a system to suppress noise. However, the passive common-mode filter has disadvantages such as a large size and high costs. In recent years, some scholars use an active filtering technology to resolve the EMI common-mode interference problem, and a new active common-mode EMI filter emerge. According to an active common-mode EMI filter in the prior art, it is generally difficult to balance a conflict between filtering performance and circuit costs.